THIS INVENTION relates to the co-production of power and hydrocarbons. In particular, the invention relates to a process for co-producing power and hydrocarbons.
Integrated Gasification Combined Cycle (IGCC) processes have environmental advantages over conventional coal-fired power plants. Synthesis gas produced by a gasifier of the IGCC process can also be used as a feedstock for co-production of liquid hydrocarbons and/or chemicals. In view of environmental pressures to reduce CO2 emissions to the atmosphere, a hydrocarbon synthesis process integrated with an IGCC process that provides the opportunity for capturing of CO2 for sequestration would be desirable.
It is possible to capture CO2 exhausted from a gas turbine unit of an IGCC process by removing the CO2 from the exhaust or stack gases. However, such exhaust or stack gases are at a low pressure and the removal of CO2 would conventionally require separation of CO2 and N2 that was introduced by combustion air fed to a combustor of the gas turbine unit. An alternative approach is to minimise the CO2 concentration in the exhaust or stack gases, e.g. by running the gas turbine on H2. In this approach, CO2 is removed from the combustion gas (mostly H2) fed to the combustor, rendering the exhaust or stack gases a mixture predominantly of N2 and water. However, H2 has a low heating value compared to other potential combustion gases containing CO and/or CH4.
It would be an advantage to provide an IGCC process integrated with a hydrocarbon production process which shows economic (i.e. capital and operating cost) benefits and environmental benefits.